Diagnostic Work Up of Ovarian Cysts

Publicationdate May 15, 2011

Ovarian cancer is the second most common ofall gynecologic malignancies. It is the leadingcause of death in this category of diseases, fre-quently presenting as a complex cystic mass.

The finding of an adnexal cyst causes consider-able anxiety in women due to the fear of malig-nancy. However, the vast majority of adnexalcysts - even in postmenopausal women - arebenign.

In this article we will focus on specific featuresof ovarian cysts that are helpful in making a dif-ferential diagnosis. We will present a roadmapfor the diagnostic work-up and management ofovarian cystic masses, based on ultrasound andMRI findings.

In Ovarian Cystic Masses II the imaging fea-tures of normal ovaries and the most commonovarian cystic masses will be presented, as wellas several less common cystic lesions.

Step 1If a cystic pelvic mass is present, the firststep is to find out if it is ovarian ornon-ovarian in origin.Step 2The next step is to determine if the lesioncan be categorized as one of the common,benign ovarian masses (simple cyst,hemorrhagic cyst, endometrioma ormature cystic teratoma), or isindeterminate.Step 3To aid in selecting the proper work-up, thefinal step is to determine whether apatient falls into a low-risk category (i.e.premenopausal women without additionalrisk factors) or a high-risk category (i.e.post-menopausal or premenopausal withadditional risk factors).

Based on these steps we can determine furthermanagement: ignore, follow-up with US, furtherevaluation with MRI or excision.

Role of imaging

Diagnostic Work up of Ovarian CystsWouter Veldhuis, Robin Smithuis, Oguz Akin and Hedvig Hricak

Department of Radiology of the University Medical Center of Utrecht, of the Rijnland hospital inLeiderdorp, the Netherlands and the Department of Radiology, Memorial Sloan-Kettering Cancer

Center, New York, USA

Diagnostic work-up

The Radiology Assistant : Diagnostic Work up of Ovarian Cysts http://radiologyassistant.nl/en/p4d85aa9a92bbb/diagnostic-work-up-of...

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Role of UltrasoundFor characterization of ovarian masses, ultra-sound is often the first-line method of choice,especially for distinguishing cystic from complexcystic-solid and solid lesions.

Role of CTCT is useful for the N- and M-staging of provenmalignant lesions.

Role of MRIFor complex lesions, primary evaluation with ul-trasound is often followed by further evaluationwith MRI.Even with MRI it is often not possible to makean accurate diagnosis of neoplastic subtype.By using MRI as an adjunct to sonography a de-lay in the treatment of potentially malignantovarian lesions is prevented.This is not only beneficial to the small numberof women who do have ovarian cancer, but alsoa proven cost-effective approach to the man-agement of sonographically indeterminate ad-nexal lesions.

If a cystic adnexal mass is present and you sus-pect an ovarian origin, the first thing to do is tryto identify the ovaries.

If the gonadal vessels lead to the lesion with noseparately identifiable normal ovaries, thenmost likely you are dealing with an ovarian le-sion.If both ovaries are separately identifiable fromthe lesion, you are dealing with a non-ovariancystic lesion, or a lesion that mimics a cysticmass.

The next step would be to check if there is uni-or bilateral disease and to look for any solidcomponents that may indicate malignancy.Also look for secondary findings like ascites, en-larged lymph nodes and peritoneal deposits.

The table shows a differential diagnosis for pos-sible cystic ovarian masses.

Ovarian or non-ovarian


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A helpful tool to identify the ovaries is to followthe ovarian veins caudally.Scroll through the CT-images and follow theright ovarian vein from where it joins the infe-rior vena cava, and the left ovarian vein whereit joins the left renal vein, until you identify theovaries.

Pattern recognition on ultrasound often allows afairly confident diagnosis of common cysticovarian masses.This means that in many cases the diagnosticwork-up is based on determining the probabilitythat we are dealing with a lesion which falls intothe category of a simple cyst, hemorrhagic cyst,endometrioma or a mature cystic teratoma(commonly referred to as a dermoid cyst).Most other cystic lesions are indeterminate andtherefore possibly malignant. These thereforerequire further evaluation, either with MRI orsurgical excision.

Simple cystUS findings that allow a confident diagnosis of asimple ovarian cyst are:

Anechoic lesion with posterior acousticenhancementUnilocularThin, smooth wallsNo solid or well-vascularized components

The US-image shows two simple cysts in theright ovary with ovarian stroma in between.The surrounding vessels are normal and thereare no vascularized septations.These were simple follicular cysts in a pre-menopausal woman.

Ultrasound pattern recognition

Scroll through the images


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Differential diagnosisMost simple cysts are functional cysts, usuallyfollicular cysts.They are commonly seen in premenopausalwomen, but functional cysts also still do occur inpostmenopausal women.Some simple cysts may turn out to be paraovar-ian or paratubal cysts.A hydrosalpinx may also mimic an ovarian cyst.Cystadenomas can also present as simple cysts,but they usually present as a large cyst in apostmenopausal woman.In a large cancer screening study from 1987 to2002 including 15,106 women of 50 years orolder, 2763 women (18%) were diagnosed witha unilocular ovarian cyst.None of these isolated unilocular cysts turnedout to be ovarian cancer (4).

In women of reproductive age, cysts up to 3 cmare a normal physiologic finding.These simple physiologic cysts do not need tobe described in the imaging report and do notrequire follow-up (1).

Cysts up to 7 cm in both pre- and post-menopausal woman are almost certainly benign.

Cysts larger than 7 cm may be difficult to assesscompletely with US and therefore further imag-ing with MR or surgical evaluation should beconsidered.

Normal ovariesFunctional cysts

Hemorrhagic ovarian cyst - HOCWhen a Graafian follicle or follicular cyst bleeds,a complex hemorrhagic ovarian cyst (HOC) isformed.

US findings that allow a confident diagnosis of ahemorrhagic ovarian cyst are:

Low risk patientCystic mass The cyst may contain a solid-appearing area with good through-transmission, without internal flow at colorDoppler, and typically with concavemargins, consistent with a blood clot

Hemorrhagic cyst


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In premenopausal women short term follow-upis recommended in hemorrhagic cysts > 5 cm.The same follow-up is recommended in earlypostmenopausal women who have a cyst withall the characteristics of a HOC Larger hemor-rhagic cysts in the early menopause and anyhemorrhagic cyst in the late menopause shouldbe considered possibly neoplastic and MRI orsurgical evaluation should be considered.

Differential diagnosisWhen hemorrhagic cysts present with diffuselow-level echoes, their appearance can be simi-lar to that of endometriomas.In the acute phase a hemorrhagic cyst may becompletely filled with low-level echoes, simulat-ing a solid mass (5).Clot in a hemorrhagic cyst may occasionallymimic a solid nodule in a neoplasm. Clot, how-ever, often has concave borders due to retrac-tion, while a true mural nodule has outwardlyconvex borders.In both cases there will be no internal flow atDoppler US and there will be good through-transmission.Hemorrhagic cysts typically resolve within 8weeks.

The ultrasound image shows multiple simpleand one complex right ovarian cyst, with diffuselow-level echos and absence of flow on DopplerUS.Note that there is good through-transmission,also through the complex cyst (blue arrow).On the T1 with fatsat the lesion remains bright,ruling out a fatty lesion.After Gd administration there is no enhance-ment, confirming that this is a cystic hemor-rhagic lesion, most likely a hemorrhagic ovariancyst, although your differential may include anendometrioma.

Hemorrhagic ovarian cyst

Hemorrhagic cyst with a clot mimicking a neoplasm.Notice absence of flow and good through-transmission(arrow)


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EndometriomaUS findings that allow a confident diagnosis ofan endometrioma are:

Homogeneous and hypoechoic massDiffuse low-level echoes (ground-glass)No internal flow at color DopplerNo enhancing nodules or solid massesIn 30% echogenic foci are seen within cystwall

In women of any age, probable endometriomasrequire initial 6-12 week follow-up to rule out ahemorrhagic cyst.Until surgically removed, endometriomas requirefollow-up with ultrasound, for example on ayearly basis.

This image from a vaginal ultrasound shows alarge hypoechoic, cystic lesion with diffuselow-level echoes and two small echogenic foci.These have been postulated to be cholesteroldeposits, but may also constitute small bloodclots or debris.It is important to differentiate these echogenicfoci from true wall nodules.Finding these echogenic foci makes the diagno-sis of an endometrioma very likely.

EndometriomaMature cystic teratomaUS findings that are characteristic of a maturecystic teratoma are:

Hypoechoic mass with hyperechoic nodule(Rokitansky nodule or dermoid plug)Usually unilocular (90%)May contain calcifications (30%)May contain hyperechoic lines caused byfloating hairMay contain a fat-fluid level, i.e. fatfloating on aqueous fluid

Shown are transvaginal ultrasound images oftwo patients that demonstrate the 'tip-of-the-iceberg' sign: acoustic shadowing from thehyperechoic part of the dermoid cyst (arrow).When misinterpreted as bowel gas, the lesionmay be overlooked.

Mature cystic teratoma


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Any other cyst - possible neoplasmAll other cystic lesions are regarded as possiblyneoplastic and therefore possibly malignant.Surgical resection is needed by an oncologic gy-naecologist, who may request prior imag-ing-based staging.

Findings indicating possible neoplasm:Large sizeWhile benign lesions can be very large, thelikelihood that a lesion is neoplasticincreases with size.Also the likelihood that a neoplastic lesionis malignant, increases with the size of thelesion.Vascularized septationsThe presence of septations indicates apossible neoplasm. When septations havea thickness of more than 3mm and arewell-vascularized - while non-specific -both increase the likelihood that aneoplasm is malignant.Vascularized solid componentsVascularized nodularities, papillaryprojections, or frank solid masses allincrease the likelihood of a neoplasticnature.Vascularized thick, irregular wallLesions with thin walls are more oftenbenign and lesions with thick, irregularwalls are more often malignant. However,there is some overlap, making wallthickness a less useful criterion. Forexample a corpus luteum cyst may alsohave a thickened, vascularized wall.Secondary findings associated withmalignant lesions:Large quantities of ascites,lymphadenopathy and peritoneal depositsare strongly associated with an increasedlikelihood of malignancy.

Benign cystic ovarian neoplasmsMalignant cystic ovarian neoplasms

Low-risk or High-risk


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Once we have determined a cystic ovarian lesionis either a probable simple cyst, hemorrhagiccyst, endometrioma or mature cystic teratoma,or is indeterminate, the next step is to place thepatient in a low-risk or high-risk group (table).

The final decision to ignore, follow or excise acystic ovarian lesion is based on:

Morphology of the lesion on US, CT or MRIRisk group (low versus high)Symptomatic lesion versus incidentalfindingAdditional findings such as ascites,lymphadenopathy or peritoneal implants

That said, the great majority of cystic ovarianlesions is benign.While the risk of malignancy does increase withage, even in post-menopausal women the riskof malignancy in a simple ovarian cyst Althoughcomplex ovarian cysts in post-menopausalwomen are also most often benign, they do re-quire further work-up, because of the chance ofmalignancy.

'the Roadmap'


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The natural history of incidentally detectedpelvic masses with benign US morpgology is notknown and therefore the optimal managementis also unknown.

The roadmap is based on the 2010 ConsensusGuidelines published in (1) and (2) and on thefindings in (3) and (4).The mentioned size cut-offs and follow-up fre-quencies are accepted practices but not ironcladrules.Local guidelines may differ based on the clinicalscenario and institutional practice preferences.

Many of the imaging criteria described in thisarticle are the same for ultrasound, CT and MRI,although of course not every feature is equallydetectable on all modalities.

Risk factorsAge is the most important risk factor for allwomen.Lesions in pre-menopausal andpost-menopausal women are managed differ-ently.Several other factors (see table) may place awoman in a higher risk category.Concordantly, the roadmap shows two path-ways, one for lower-risk and one for higher-riskpatients.


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MRI protocolThere are many possible 'Pelvic/Ovarian mass'protocols.

The basic building blocks are simple and are thesame for all protocols:

High-resolution, T2W sequence withoutfatsat, in at least 2 planes -> anatomyT1W sequence without fatsat, orpreferably a T1W opposed-phase sequence-> detection of fat, in teratomaT1W sequence with fatsat -> mainly forthe identification of blood products and forcorrelation to post-contrast T1W imagesA Proton-Density or T1W sequenceextending to the upper abdomen -> nodaldisease. Some institutions may prefer toskip this sequence in favor of a staging CTor PET/CT.A T1W sequence with fatsat afteradministration of Gadolinium ->enhancement of solid lesions or lesioncomponents.A diffusion-weighted sequence with ahighest b-value of 500- 1000 s/mm2 ->detection (not staging) of lymph nodesand detection of peritoneal deposits.

A very short protocol may consist of only 1, 2and 3 (e.g., when the request is to 'rule out anovarian mass').Many radiologists prefer a slightly more compre-hensive protocol including 4, and often 5.When the clinical setting is characterization orstaging of a known ovarian lesion, 4 (or CT) and5 should always be included.

The role of diffusion-weighted MRI is yet to bedetermined, but DWI is a useful aid in the de-tection of lymph nodes, tumors and peritonealdeposits.For the purpose of detection, the DW imagesare sometimes fused with (superimposed on)anatomical T2W images.DWI cannot discriminate benign from metastaticlymph nodes.

Further differences in protocols all arise as vari-ations on this simple theme.For example:

T2W images in more than 2 planes, orobliquely angled orthogonal to theanatomic structure of interest, are often

MRI protocol - which sequences, and why


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useful for cervical or uterine-bodypathology. -Variations in FOV, with a larger FOV tocover the whole pelvis and a smaller FOVcentered on the lesion of interest.Post-contrast images in 2 or even 3planes.Sagittal T2W cine acquisition for recordinguterine wall contractions.

MR imaging is a valuable adjunct to US, as it al-lows identification of blood products within hem-orrhagic masses that may mimic solid tumor atUS.Fat-suppressed T1-weighted MR images may re-veal small amounts of fat, which allows the di-agnosis of a mature teratoma ('dermoid').Contrast-enhanced T1-weighted MR imaging de-picts features of malignancy such as enhancingmural nodules and/or enhancing solid areas withor without necrosis (3).

These MR images show a lesion with high signalon T1.This indicates either blood, other high proteincontent or fat.On the image with fat-saturation there is sup-pression of the signal.This means that we are dealing with a fat-con-tainig lesion, i.e. a mature cystic teratoma.

The US image shows an echogenic lesion.The corresponding lesion has a high signal onthe T1-weighted MR image. This indicates eitherblood, high protein or fat.On the image with fat-saturation there is nosuppression of the signal.This means that we are dealing with a blood-containig lesion, i.e. most likely a hemorrhagiccyst.

Management of Asymptomatic Ovarian and Other Adnexal Cysts Imaged at US: Society of Radiologists inUltrasound Consensus Conference Statementby Deborah Levine et alSeptember 2010 Radiology, 256, 943-954.

1.

ESUR guidelines for MR imaging of the sonographically indeterminate adnexal mass: an algorithmicapproachby Spencer JA et alEur Radiol. 2010 Jan;20(1):25-35.

2.

MR Imaging of the Sonographically Indeterminate Adnexal Massby John A. Spencer et al

3.


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September 2010 Radiology, 256, 677-694.Risk of malignancy in unilocular ovarian cystic tumors less than 10 centimeters in diameterby Modesitt SC, Pavlik EJ, Ueland FR, DePriest PD, Kryscio RJ, van Nagell JR Jr.Obstet Gynecol. 2003 Sep;102(3):594-9.

4.

Adnexal Masses: US Characterization and Reportingby Douglas L. Brown, MD, Kika M. Dudiak, MD and Faye C. Laing, MDFebruary 2010 Radiology, 254, 342-354.

5.

Nonovarian Cystic Lesions of the Pelvisby Penelope L. Moyle et alJuly 2010 RadioGraphics, 30, 921-938.

6.

Endometriosis: Radiologic-Pathologic Correlationby Paula J. Woodward et alRadioGraphics 2001; 21:193-216.

7.

Magnetic resonance imaging of adnexal massesby Rajkotia K, Veeramani M, Macura KJTop Magn Reson Imaging 2006; 17:379-97

8.

Clinical Decision Making Using Ovarian Cancer Risk Assessmentby Michael P. Stany et alAJR 2010; 194:337-342

9.

The Likelihood Ratio of Sonographic Findings for the Diagnosis of Hemorrhagic Ovarian Cystsby Maitray D. Patel, MD, Vickie A. Feldstein, MD and Roy A. Filly, MD2005 J Ultrasound Med 24:607-614

10.

Role of Transvaginal Sonography in the Diagnosis of Peritoneal Inclusion Cystsby Stefano Guerriero et al2004 J Ultrasound Med 23:1193-1200

11.

Sonographic Spectrum of Hemorrhagic Ovarian Cystsby Kiran A. JainJ Ultrasound Med 21:879-886

12.


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Diagnostic Work Up of Ovarian Cysts

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